Project Summary/Abstract The goal of this project is to better understand how interleukin-27 (IL-27) signaling in intestinal epithelial cells (IEC) can promote intestinal barrier integrity in the setting of ethanol intoxication and burn injury. Burn injuries account for 40,000 hospitalizations every year, with nearly 50% of patients having detectable blood alcohol levels at the time of admission. Patients intoxicated at the time of burn injury have worse clinical outcomes, including longer hospital stays, increased rates of infection, and increased morbidity and mortality. Detrimental sequelae of burn injuries are the result of the breakdown in the gut barrier, which normally encloses the largest reservoir of bacteria and harmful bacterial products. Ethanol intoxication at the time of burn injury exacerbates this post-burn pathogenesis, leading to exacerbated gut barrier dysfunction and leakiness. This gut barrier breakdown leads to multiple organ failure, sepsis, and death following injury. A major contributing factor to gut leakiness is attributed to hypoxic conditions in the gut, leading to stabilization of hypoxia inducible factor 1a (HIF1a). Our lab has previously found that inhibition of HIF1a with PX-478 leads to improved outcomes in ethanol intoxication and burn injury, including improved gut transit, decreased gut permeability, and reduced inflammation. However, the mechanism by which this occurs is unknown. We have also found that expression of the IL-27 receptor was restored in IECs following inhibition of HIF1a following ethanol intoxication and burn injury. Ethanol intoxication and burn injury led to reduced IL-27 producing cells in the lamina propria, which is accompanied by reduced IL-27 receptor expression in IECs. IL-27 has been implicated in restoring intestinal barrier integrity in other models of intestinal inflammation, therefore leading us to hypothesize that restoring IL- 27 signaling following ethanol intoxication and burn injury will lead to improved barrier integrity. In Aim 1, we will determine perturbations in IL-27 signaling in the intestine following HIF1a inhibition in ethanol intoxication and burn injury. In Aim 2, we will elucidate the mechanism by which IL-27 signaling restores intestinal epithelial barrier integrity by observing changes in phosphorylation of downstream signaling molecules STAT1/STAT3, IEC proliferation, and tight junction expression. Overall, this study will aid in our understanding of how we can restore intestinal barrier function following ethanol intoxication and burn injury.